| Abstract: | Causes and mechanisms of stress corrosion cracking The paper provides a synopsis of the causes and mechanisms of stress corrosion cracking discussed at the present time. The discussion covers: selective metal dissolution (formation of cover layers, influence of lattice imperfections on the anodic metal dissolution, crack spreading rate, anodic hydrogen embrittlement); adsorption and brittle fracture (energy balance, atomistic and electro-chemical aspects); metallurgy (plastic deformation, alloying influence, sliding condition); fracture mechanics (crack formation and growth). Particularly important is the formation of cover layers where stress corrosion cracking depends on a certain ratio of the rate at which the cover layer is reformed and the rate at which surfaces free from cover layer are formed at the bottom of the crack. At high crack expansion rates, the adsorption-brittle fracture mechanism may play a part, as it tends to lower the cohesion at the bottom of the crack. As the crack represents an ideally sharp notch, it is possible to apply the linear elastic fracture mechanics to the crack expansion phenomena. |
